Potassium permanganate is prepared by fusing pyrolusite with caustic potash in the presence of air or some oxidising agent which gives a green mass. The green mass is then extracted with water and treated with a current of `Cl_2` to form potassium permanganate. In the laboratory, it is prepared by oxidising a manganese (II) salt by peroxosulphate. It acts as an oxidising agent in neutral, alkaline or acidic solutions.
Name the green mass obtained by heating pyrolusite with KOH in the presence of air and its reaction equation.

Explanation

To solve the question, we need to identify the green mass formed by heating pyrolusite (MnO2) with caustic potash (KOH) in the presence of air, and also provide the reaction equation for this process.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this process are pyrolusite (MnO2) and caustic potash (KOH).
- Air (which provides oxygen) is also involved in the reaction.

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